Abrasion testing machine



y 1932- J. LAMBOURN ABRASION TESTING MACHINE Filed Aug. 3, 1927 2 Sheets-Sheet l [N VENZOR a ATTORNEY BY V,

y 12, 1932- L. J; LAMBOURN ABRASION TESTING MACHINE Filed Aug. 5, 1927 2 Sheets-Sheet 2 MFY ORNEY Patented July 12, 1932 UNITED STATES PATENT OFFICE LEONARD JOHN LAMBOURN, OF FORT DUNLOP, ERDINGTON, BIRMINGHAM, ENGLAND,

ASSIGNOR TO DUNLOP TIRE AND RUBBER CORPORATION, OF BUFFALO, NEW YORK.

A CORPORATION OF NEW YORK ABRASION TESTING MACHINE Application filed August 3, 1927, Serial No. 210,247, and in Great Britain September 1, 1926.

This invention relates to abrasion testing machines of the type wherein the sample to be tested, preferabl of wheel-like form and hereinafter call the test piece, is abraded in consequence of its rotation in relation to an abrasive member, preferably a rotary disc and hereinafter called the-abrasive disc.

This type of machine is particularly adapted to the testing of tire tread rubber inas- 1 much as it successfully simulates the conditions of usage of vehicle wheel tires.

In general, such machines usually include an idler disc of abrasive material adapted to be rotated by the test piece which itself is rotated by a suitable power means. To augment the abrasive action, slip or drag is caused to occur between the test piece and the abrasive disc. Various means have been proposed to produce the required slip, for instance, the test piece has been arranged obliquely to the direction of rotationof the abraslve disc. Or alternatively the abrasive disc has been retarded by braking or weight- It will be apparent that the degree of drive transmitted to the disc through the test piece is necessarily influenced b the nature, for instance the resiliency o the test piece. Therefore, if the pressure between the test 80 piece and the disc, the retardation of the said disc, and the speed of rotation of the test iece are all constant then the degree of slip Between the test piece and the disc will necessarily vary according to the nature of the said test piece.

As the test is a comparative test it will be apparent that the conditions, particularly the degree of sli under which each test is carried out must e similar or incorrect conclusions will result.

In machines as hitherto constructed, no provision has been made to secure a constant degree of slip or drag, and it is the'object of this invention to provide a machine wherein such a provision is incorporated, for the purpose, as aforesaid, of ensuring that each test is carried out under conditions as nearly alike as possible.

According to this invention therefore, I W ensure the occurrence of the required consequences occasioning abrasion, for instance constant slip or drag between the abrasive member and the test piece, preferably providing means whereby the relative speed of the test piece and abrasive member may be controlled, for instance ke t constant irrespective of the degree of rive transmitted from one to the other.

Preferably I provide means in association with retardation means for the abrasive disc, whereby the speed of the said disc may be kept constant irrespective of the degree of drive transmitted by the test piece.

In order that the said invention may be clearly understood and readily carried into effect the same will now be described with reference to the accompanying drawings in which- Fig. 1 is a diagrammatic plan view of apparatus according to my invention.

Fig. 2 is a perspective view of such apparatus.

Fig. 3 is a view of a modification.

In the preferred embodiment of my invention illustrated in the drawings, the test piece 1 is rotated by an electric motor 2 the speed of which is indicated by a tachometer 3 and controlled by a rheostat 4 to ensure that the said test piece is rotated at an exactly constant speed irrespective of extraneous conditions such as alteration in the current actuating the motor. As shown in the drawings, the rheostat 4 is preferably arranged across the armature of the motor; the line thereof being connected to the mains 5 via a suitable starter 6 and switch 7.

The test piece 1 contacts and rotates by friction an abrasive disc 8, means being provided to exert the required pressure therebetween. Preferably, as shown in the drawings, the test piece is arranged at the end of a pivotal bracket 9,--fulcrumed at 10 between suitable supports 11,-and carrying an adjustable, counterbalancing wei ht 12.

To occasion slip between the a rasive disc and the test piece I preferably provide means adapted to retard, against the drive exerted by the said test piece, the rotation of the said abrasive disc. As shown in the drawings, such means consist in associating 100 with the said disc an electro-magnetic brake comprisinga copper disc 13,-rigid with the said abrasive discand adapted to rotate between the poles of an electro-magnet 14- eddy currents being thereby occasioned in the said disc to retard its rotation.

In order to keep the degree of slip constant throughout a test it is necessaryit being understood that the speed of the test piece iskept constant-that the speed of the abrasive disc should be kept constant also, irrespective of the varying degree of drive transmitted to it by the test piece.

And according to this invention, provision is made to achieve that end-the same as shown in the drawings including a tachometer 15to indicate the speed of the abrasive disc-and means to vary the degree of retardation of the said disc. The said means preferably consist in varying, with the aid of a rheostat 16 the current energizing the magnet of the brake 14,-thereby to vary the retardation of the abrasive disc aforesaid. As'shown in the drawings the magnet circuit preferably also includes a fixed resistance in the form of a'lamp 17.

I preferably provide means whereby the total degree of slip over a. given periodduring a complete test for instance-may be ascertained. The same as shown in the drawings comprise two counters 18 and '19 adapted respectively to record the revolutions of the abrasive disc and of the test piece; it being apparent that the slip of the test piece relative to the abrasive disc is readily calculable from the readings of the two instruments.

To keep the surface of the abrasive disc clean and free from particles abraded from the test piece I ma provide a rotary wire brush 20-arrange obliquely to occasion brushin of the surface of the said disc and/or may provide an air pipe 21 adapted to clean the said surface by suction or draught.

It is not to be construed that I am limited to the precise embodiment of my invention described as the same as set out in the statement thereof may be carried into effect in a variety of ways.

For instance, the eddy-current brake may be replaced by an adjustable brake as illustrated in Fi 3 (attached).

Instead o the copper disc 13, I may have a pulley 22, rigid with the said abrasive disc 8, connected to the pulley 23 of a motor 24 by means of a belt 25. Retardation of the abrasive disc 8 would then be produced according to the force required to turn the pulley 23. This retardation could be made adjustable by having a variable resistance 26 across the armature terminals of a motor 24.

Various modifications may be made by those skilled in the art without departing from the invention as described in the following claims.

ference in relative motion between the test piece and the abrasive member is effected and separate means for indicating, respectively, the s eed of said abrasive member and the spec of said test piece whereby the degree of slip at any instant can be determined.

2. An abrasion testing machine of the character described comprising a movably supported abrasive member, means for causing a test piece to drive said member and means controlling the speed of said abrasive member and separate means indicating respectively the speed of said abrasive member and the speed of said test piece whereby the degree of slip at any given instant can be determined.

3. An abrasive testing machine of the character described comprising a movably supported abrasive member, means for supporting a test piece in cooperative engagement therewith, driving means effective to move both the test piece and the abrasive member, retarding means elfective to cause a slip or difference in relative motion between the test piece and abrasive member, means for varying the retardin action of the latter and separate means for indicating respectively the speed of the retarding member and the test piece.

4. An abrasive testing machine of the character described comp 'sing a rotatably sup-' ported abrasive member, means for rotatahly supporting a test piece in cooperative engagement therewith, driving means effective to rotate both the abrading member and the test piece, retarding means effective to cause a relative slip between the test piece and the abrasive member, means for varying the retarding action of the retarding means, and separate tachometers indicating respectively the speed of said abrasive member and said test piece whereby the degree of slip at any instant can be observed.

5. An abrasive testing machine of the character described comprising a rotatably supported abrasive member, means for rotatably supporting a test piece in cooperative engagement therewith, driving means effective to rotate both the abrading member and the test piece, retarding means effective to cause a relative slip between the test piece and the abrasive member, means for varying the retarding action of the retarding means, and separate tachometers indicating respectively the speed of said abrasive member and said test piece whereby the degree of slip at any instant can be observed and respective counfers indicating the number of revolutions of the test piece and abrasive member whereby the total amount of, slip over a, given riodl during a complete test maybe ascertained.

In witness whereof, I have hereunto signed my name.

. LEONE JOHN RAMON. 

